US20100142042A1 - Microscope and microscopy method for space-resolved measurement of a predetermined structure, in particular a structure of a lithographic mask - Google Patents
Microscope and microscopy method for space-resolved measurement of a predetermined structure, in particular a structure of a lithographic mask Download PDFInfo
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- US20100142042A1 US20100142042A1 US12/517,583 US51758307A US2010142042A1 US 20100142042 A1 US20100142042 A1 US 20100142042A1 US 51758307 A US51758307 A US 51758307A US 2010142042 A1 US2010142042 A1 US 2010142042A1
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- 238000005259 measurement Methods 0.000 title claims abstract description 34
- 238000000034 method Methods 0.000 title claims description 22
- 238000000386 microscopy Methods 0.000 title claims description 7
- 230000010287 polarization Effects 0.000 claims abstract description 164
- 230000003287 optical effect Effects 0.000 claims abstract description 88
- 230000005670 electromagnetic radiation Effects 0.000 claims abstract description 47
- 230000005855 radiation Effects 0.000 claims abstract description 19
- 238000005286 illumination Methods 0.000 claims description 21
- 238000001514 detection method Methods 0.000 claims description 19
- 238000003384 imaging method Methods 0.000 claims description 16
- 230000001419 dependent effect Effects 0.000 claims description 11
- 230000005540 biological transmission Effects 0.000 claims description 8
- 230000004075 alteration Effects 0.000 claims description 3
- 230000001678 irradiating effect Effects 0.000 claims description 3
- 230000000694 effects Effects 0.000 description 4
- 230000008859 change Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000012634 optical imaging Methods 0.000 description 1
- 238000000711 polarimetry Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
- G03F7/70605—Workpiece metrology
- G03F7/70616—Monitoring the printed patterns
- G03F7/70625—Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B21/00—Microscopes
- G02B21/0004—Microscopes specially adapted for specific applications
- G02B21/0092—Polarisation microscopes
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B21/00—Microscopes
- G02B21/06—Means for illuminating specimens
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B21/00—Microscopes
- G02B21/16—Microscopes adapted for ultraviolet illumination ; Fluorescence microscopes
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/68—Preparation processes not covered by groups G03F1/20 - G03F1/50
- G03F1/82—Auxiliary processes, e.g. cleaning or inspecting
- G03F1/84—Inspecting
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
- G03F7/70605—Workpiece metrology
- G03F7/70616—Monitoring the printed patterns
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- G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
- G02B27/283—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising used for beam splitting or combining
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/68—Preparation processes not covered by groups G03F1/20 - G03F1/50
Definitions
- the predetermined structure is imaged onto a detector, with the contrast in the optical image on the detector strongly depending on the polarization condition of the irradiated light.
- effects of electromagnetic interaction can cause a variation in the position of an edge of the structure in the optical image, depending on the polarization condition of the electromagnetic radiation used to illuminate the structure.
- the polarization condition of the electromagnetic radiation for illumination of the predetermined structure has not been taken into account in such microscopes so far. Also, changes in polarization properties, which change results from the optics of the microscope, e.g. from polarization-dependent properties of the lens coatings, intrinsic birefringence, stress-induced birefringence of glasses, as well as, in particular, of mirrors and beam splitters, are not taken into account and lead to errors of measurement.
- the object is achieved by a microscope for space-resolved measurement of a predetermined structure, said microscope comprising a source of radiation, which emits electromagnetic radiation of a predetermined wavelength; an optical system, which irradiates electromagnetic radiation onto the structure to be measured and images said structure, irradiated with the electromagnetic radiation, onto a detector,
- the optical system has two eigen polarization conditions and the apparatus includes a polarization module by which a polarization condition can be set for the electromagnetic radiation of the source of radiation, which condition comprises only those components of a known quantity which correspond to the eigen polarization conditions.
- the eigen polarization conditions (intrinsic polarization conditions) of the optical system are polarization conditions which are not modified when passing through the optical system, this has the advantageous effect that the optical system does not lead to any polarization-dependent deterioration during measurement.
- the polarization-dependent error can then be taken into account, for example computationally, during imaging onto the detector, so that a very high precision of measurement can be achieved.
- the polarization condition is defined as precisely as possible according to the present invention. Therefore, preferably no variation of the polarization condition is effected during the measurement process.
- the microscope can measure the predetermined structure by transmission and/or reflection. If it measures the structure by reflection, preferably at least one optical element of the optical system is employed for both illumination and detection.
- the microscope can also be provided such that switching between transmission measurement and reflection measurement is possible.
- the optical system of the microscope may comprise illumination optics for irradiating the electromagnetic radiation onto the structure to be measured, as well as detection optics for imaging the irradiated structure onto the detector, wherein the eigen polarization conditions of the illumination optics and/or of the detection optics correspond to the eigen polarization conditions of the optical system.
- the eigen polarization conditions of the illumination optics and of the detection optics may coincide and, thus, correspond to the eigen polarization conditions of the optical system.
- the eigen polarization conditions of the optical system are linear polarization conditions and the polarization condition of the electromagnetic radiation which can be set by means of the polarization module coincides with one of said two linear polarization conditions.
- the eigen polarization conditions of the predetermined structure are frequently also linear polarization conditions, so that also the structure itself does not exert any polarization-dependent negative influence on measurement.
- the predetermined structure may generally comprise two eigen polarization conditions, wherein at least one of said two eigen polarization conditions of the predetermined structure coincides with at least one of the eigen polarization conditions of the optical system.
- This may be realized by a suitable design of the optical system, a suitable selection of the structure and/or suitable orientation of the structure relative to the optical system.
- the optical system may further comprise an eigen polarization unit, by which the two eigen polarization conditions of the optical system can be modified.
- the eigen polarization conditions of the optical system can be adapted to the respective eigen polarization conditions of the predetermined structure to be examined (which generally comprises elliptical eigen polarization conditions).
- the polarization module can be used to set a polarization condition of the electromagnetic radiation under which the contrast of the image of the predetermined structure recorded by the detector is at a maximum.
- the microscope serves to measure a structure on a lithographic mask or on a semi-conductor wafer.
- the source of radiation is, in particular, a laser source. It may emit in the deep UV-range, for example at a wavelength of 193 nm.
- the predetermined maximum wavefront error of claim 8 may be ⁇ /10, ⁇ /50, or even ⁇ /100, wherein ⁇ refers to the predetermined wavelength of the electromagnetic radiation of the source of radiation.
- a microscopy method for space-resolved measurement of a predetermined structure wherein a source of radiation emits electromagnetic radiation of a predetermined wavelength, an optical system having two eigen polarization conditions irradiates the electromagnetic radiation onto the structure to be measured and images said structure, irradiated with said electromagnetic radiation, onto a detector, wherein a polarization condition is set for the electromagnetic radiation of the source or radiation, which polarization condition comprises only components of a known quantity which correspond to the eigen polarization conditions.
- the predetermined structure can be measured by reflection and/or transmission. Further, it is possible to carry out the reflection and transmission measurements after each other in any desired sequence.
- the optical system may comprise illumination optics for irradiating the electromagnetic radiation onto the predetermined structure, and detection optics for imaging the irradiated structure onto a detector, wherein the eigen polarization conditions of the illumination optics and/or of the detection optics correspond to the eigen polarization conditions of the optical system.
- the eigen polarization conditions of the illumination optics and of the detection optics may coincide and, thus, correspond to the eigen polarization conditions of the optical system.
- the eigen polarization conditions may be linear polarization conditions and the set polarization condition of the electromagnetic radiation may coincide with one of said two linear polarization conditions.
- the predetermined structure may have two eigen polarization conditions, wherein at least one of said two eigen polarization conditions of the predetermined structure coincides with at least one of the eigen polarization conditions of the optical system.
- the optical system may comprise an eigen polarization condition, by which the two eigen polarization conditions of the optical system can be modified. This allows the eigen polarization conditions of the optical system to be adapted to the predetermined structure to be examined respectively.
- microscopy method in particular, structures on a lithographic mask or on a semiconductor wafer are measured.
- the microscopy method can be improved according to the dependent method claims.
- the maximum wavefront error in claim 21 may be ⁇ /10, ⁇ /50, or even ⁇ /100.
- FIG. 1 shows a first embodiment of the microscope according to the invention
- FIG. 2 shows a schematic top view of the lithographic mask 8 of FIG. 1 .
- FIG. 3 shows a second embodiment of the microscope according to the invention.
- the measurement apparatus 1 for space-resolved measurement of a structure (in this case, on a lithographic mask 8 ) comprises a source of radiation 2 emitting electromagnetic radiation 3 of a wavelength of 193 nm, as well as, in this order, a polarization module 4 , a beam splitter 5 , and imaging optics 6 .
- the polarization module 4 , the beam splitter 5 , and the imaging optics 6 together form illumination optics 7 , which irradiate the lithographic mask 8 with the electromagnetic radiation 3 coming from the source of radiation 2 .
- the radiation reflected by the lithographic mask 8 passes through the imaging optics 6 and is transmitted by the beam splitter 5 (at least partially) to a detector 9 , which is arranged following the beam splitter 5 and may be provided, for example, as an LCD detector.
- the imaging optics 6 together with the beam splitter 5 , form detection optics 10 for the optical radiation reflected by the lithographic mask 8 .
- the detection optics 10 and the illumination optics 7 together form an optical system 3 .
- the imaging optics 6 are represented only schematically. They can be provided, in particular, as microscope optics, comprising objective optics and tube optics, and can, thus, comprise several optical imaging elements, wherein the beam splitter 5 can be arranged between these imaging elements (preferably in an infinite beam path).
- the measurement apparatus 1 further comprises a mask stage 11 , which is provided, for example, as an x-y stage, to allow positioning of predetermined test structures 12 of the lithographic mask 8 in the detection region of the measurement apparatus 1 .
- FIG. 2 schematically shows several test structures 12 in a top view of the lithographic mask 8 .
- said test structures can be provided as crosses; the representation in FIG. 2 is not to scale, and the size of the test structures is shown strongly enlarged.
- the mask structures (not shown) are present which are required for exposure of a wafer in a lithographic exposure apparatus.
- a control unit 14 ( FIG. 1 ) is provided, which is connected to the mask stage 11 , to the detector 9 and optionally also to the source of radiation 2 , as well as to the polarization module 4 .
- the optical system 13 of the measurement apparatus 1 has the eigen polarization conditions Z 1 and Z 2 schematically represented in FIG. 1 .
- Both eigen polarization conditions Z 1 and Z 2 are linear polarization conditions, which are oriented in the x-direction as well as perpendicular to the drawing plane. These eigen polarizations conditions Z 1 and Z 2 may be caused, for example, by the beam splitter 5 .
- the imaging optics 6 are regarded here as not influencing the polarization condition of the electromagnetic radiation transmitted through them.
- the polarization condition of the electromagnetic radiation 3 emitted by the source of radiation 2 is indicated. As schematically indicated by the circle in the drawing, this may be, for example, a circular polarization PL.
- the polarization module 4 is adapted to convert the electromagnetic radiation 3 having said circular polarization into a linear polarization coinciding with the eigen polarization condition Z 1 , or to transmit only this component, so that the electromagnetic radiation incident on the beam splitter 5 has a polarization P 1 which coincides with the first eigen polarization condition Z 1 of the optical system 13 .
- This has the advantageous effect that the polarization P 2 of the electromagnetic radiation 3 in the illumination optics 7 is not changed.
- the polarization module may be adapted such that electromagnetic radiation of any polarization is converted to the eigen polarization condition of the optical system or only the corresponding component is transmitted.
- the polarization condition of the magnetic radiation is not changed even by reflection at the test structure 12 , because a first eigen polarization condition T 1 of the test structure coincides with the polarization condition P 2 of the electromagnetic radiation incident on the test structure 12 .
- the first eigen polarization condition T 1 of the test structure is represented together with the second eigen polarization condition T 2 of the test structure in FIG. 2 (these are linear polarization conditions).
- the polarization P 2 , P 3 of the reflected electromagnetic radiation passing through the detection optics 10 is not modified, because the detection optics 10 have the same eigen polarization conditions Z 1 and Z 2 as the illumination optics 7 .
- the reflected radiation, having the linear polarization P 3 schematically indicated in FIG. 1 is then incident on the detector 9 .
- the test structure can be measured by the measurement apparatus 1 with extreme precision.
- FIG. 3 shows an improvement of the measurement apparatus of FIG. 1 , wherein the same elements are designated by the same reference numerals and, for description thereof, reference is made to the above statements.
- an eigen polarization unit 15 which causes the eigen polarization conditions Z 1 and Z 2 of the optical system 13 to be elliptically polarized conditions.
- the polarization module 4 is provided such that the electromagnetic radiation 3 coming from the polarization module 4 is elliptically polarized (according to one of the eigen polarization conditions Z 1 and Z 2 ).
- the embodiment of FIG. 3 also achieves the advantage that the optical system 13 does not change the polarization condition which coincides with one of its eigen polarization conditions Z 1 , Z 2 .
- the eigen polarization unit 15 can be used to correct polarization aberrations such that a maximum polarization-dependent wavefront error of ⁇ /10 or ⁇ /50, or ⁇ /100, respectively, is not exceeded.
- the eigen polarization unit 15 can be controllable such that different eigen polarization conditions can be set under the control of the control unit 14 . Preferably, these are defined depending on the eigen polarization conditions T 1 , T 2 of the test structures 12 to be examined.
Abstract
Description
- In a microscope for space-resolved measurement of a predetermined structure and a corresponding microscopy method, the predetermined structure is imaged onto a detector, with the contrast in the optical image on the detector strongly depending on the polarization condition of the irradiated light. Moreover, effects of electromagnetic interaction can cause a variation in the position of an edge of the structure in the optical image, depending on the polarization condition of the electromagnetic radiation used to illuminate the structure.
- The polarization condition of the electromagnetic radiation for illumination of the predetermined structure has not been taken into account in such microscopes so far. Also, changes in polarization properties, which change results from the optics of the microscope, e.g. from polarization-dependent properties of the lens coatings, intrinsic birefringence, stress-induced birefringence of glasses, as well as, in particular, of mirrors and beam splitters, are not taken into account and lead to errors of measurement.
- In view thereof, it is an object of the invention to provide a microscope and a microscopy method for space-resolved measurement of a predetermined structure, which allows higher accuracy to be achieved.
- According to the invention, the object is achieved by a microscope for space-resolved measurement of a predetermined structure, said microscope comprising a source of radiation, which emits electromagnetic radiation of a predetermined wavelength; an optical system, which irradiates electromagnetic radiation onto the structure to be measured and images said structure, irradiated with the electromagnetic radiation, onto a detector,
- wherein the optical system has two eigen polarization conditions and the apparatus includes a polarization module by which a polarization condition can be set for the electromagnetic radiation of the source of radiation, which condition comprises only those components of a known quantity which correspond to the eigen polarization conditions.
- Since the eigen polarization conditions (intrinsic polarization conditions) of the optical system are polarization conditions which are not modified when passing through the optical system, this has the advantageous effect that the optical system does not lead to any polarization-dependent deterioration during measurement. On the basis of the known amounts of those components of the electromagnetic radiation for illumination of the structure which correspond to the eigen polarization conditions, the polarization-dependent error can then be taken into account, for example computationally, during imaging onto the detector, so that a very high precision of measurement can be achieved.
- In contrast to the measuring methods of imaging polarimetry, which aim to analyze the polarization condition in the image by varying the polarization condition in the illumination and imaging beam paths, the polarization condition is defined as precisely as possible according to the present invention. Therefore, preferably no variation of the polarization condition is effected during the measurement process.
- The microscope can measure the predetermined structure by transmission and/or reflection. If it measures the structure by reflection, preferably at least one optical element of the optical system is employed for both illumination and detection. The microscope can also be provided such that switching between transmission measurement and reflection measurement is possible.
- The optical system of the microscope may comprise illumination optics for irradiating the electromagnetic radiation onto the structure to be measured, as well as detection optics for imaging the irradiated structure onto the detector, wherein the eigen polarization conditions of the illumination optics and/or of the detection optics correspond to the eigen polarization conditions of the optical system. In particular, the eigen polarization conditions of the illumination optics and of the detection optics may coincide and, thus, correspond to the eigen polarization conditions of the optical system.
- In particular, the eigen polarization conditions of the optical system are linear polarization conditions and the polarization condition of the electromagnetic radiation which can be set by means of the polarization module coincides with one of said two linear polarization conditions. This is particularly easy to realize. In particular, the eigen polarization conditions of the predetermined structure are frequently also linear polarization conditions, so that also the structure itself does not exert any polarization-dependent negative influence on measurement. The predetermined structure may generally comprise two eigen polarization conditions, wherein at least one of said two eigen polarization conditions of the predetermined structure coincides with at least one of the eigen polarization conditions of the optical system.
- This may be realized by a suitable design of the optical system, a suitable selection of the structure and/or suitable orientation of the structure relative to the optical system.
- The optical system may further comprise an eigen polarization unit, by which the two eigen polarization conditions of the optical system can be modified. Thus, the eigen polarization conditions of the optical system can be adapted to the respective eigen polarization conditions of the predetermined structure to be examined (which generally comprises elliptical eigen polarization conditions).
- In particular, the polarization module can be used to set a polarization condition of the electromagnetic radiation under which the contrast of the image of the predetermined structure recorded by the detector is at a maximum.
- In particular, the microscope serves to measure a structure on a lithographic mask or on a semi-conductor wafer.
- The source of radiation is, in particular, a laser source. It may emit in the deep UV-range, for example at a wavelength of 193 nm.
- Improvements of the microscope are further indicated in
dependent claims 2 to 12. The predetermined maximum wavefront error ofclaim 8 may be λ/10, λ/50, or even λ/100, wherein λ refers to the predetermined wavelength of the electromagnetic radiation of the source of radiation. - Further, a microscopy method for space-resolved measurement of a predetermined structure is provided, wherein a source of radiation emits electromagnetic radiation of a predetermined wavelength, an optical system having two eigen polarization conditions irradiates the electromagnetic radiation onto the structure to be measured and images said structure, irradiated with said electromagnetic radiation, onto a detector, wherein a polarization condition is set for the electromagnetic radiation of the source or radiation, which polarization condition comprises only components of a known quantity which correspond to the eigen polarization conditions.
- This has the effect that the optical system causes no polarization-dependent deterioration during measurement of the predetermined structure.
- The predetermined structure can be measured by reflection and/or transmission. Further, it is possible to carry out the reflection and transmission measurements after each other in any desired sequence.
- The optical system may comprise illumination optics for irradiating the electromagnetic radiation onto the predetermined structure, and detection optics for imaging the irradiated structure onto a detector, wherein the eigen polarization conditions of the illumination optics and/or of the detection optics correspond to the eigen polarization conditions of the optical system. In particular, the eigen polarization conditions of the illumination optics and of the detection optics may coincide and, thus, correspond to the eigen polarization conditions of the optical system.
- Further the eigen polarization conditions may be linear polarization conditions and the set polarization condition of the electromagnetic radiation may coincide with one of said two linear polarization conditions.
- The predetermined structure may have two eigen polarization conditions, wherein at least one of said two eigen polarization conditions of the predetermined structure coincides with at least one of the eigen polarization conditions of the optical system.
- The optical system may comprise an eigen polarization condition, by which the two eigen polarization conditions of the optical system can be modified. This allows the eigen polarization conditions of the optical system to be adapted to the predetermined structure to be examined respectively.
- Further, it is possible to set a polarization condition of the electromagnetic radiation under which the contrast of the image of the predetermined structure recorded by means of the detector becomes maximal.
- Using the microscopy method, in particular, structures on a lithographic mask or on a semiconductor wafer are measured.
- The microscopy method can be improved according to the dependent method claims. The maximum wavefront error in claim 21 may be λ/10, λ/50, or even λ/100.
- It is evident that the features mentioned above and those mentioned below, which are yet to be explained, can be used not only in the combinations mentioned, but also in any other combinations, or alone, without departing from the scope of the present invention.
- The invention will be explained in more detail below, by way of example and with reference to the enclosed Figures, which also disclose essential features of the invention. In the drawings:
-
FIG. 1 shows a first embodiment of the microscope according to the invention; -
FIG. 2 shows a schematic top view of thelithographic mask 8 ofFIG. 1 , and -
FIG. 3 shows a second embodiment of the microscope according to the invention. - In the embodiment shown in
FIG. 1 , themeasurement apparatus 1 according to the invention, for space-resolved measurement of a structure (in this case, on a lithographic mask 8) comprises a source ofradiation 2 emitting electromagnetic radiation 3 of a wavelength of 193 nm, as well as, in this order, apolarization module 4, abeam splitter 5, andimaging optics 6. - The
polarization module 4, thebeam splitter 5, and theimaging optics 6 together formillumination optics 7, which irradiate thelithographic mask 8 with the electromagnetic radiation 3 coming from the source ofradiation 2. - The radiation reflected by the
lithographic mask 8 passes through theimaging optics 6 and is transmitted by the beam splitter 5 (at least partially) to adetector 9, which is arranged following thebeam splitter 5 and may be provided, for example, as an LCD detector. Theimaging optics 6, together with thebeam splitter 5,form detection optics 10 for the optical radiation reflected by thelithographic mask 8. Thedetection optics 10 and theillumination optics 7 together form an optical system 3. - In this case, the
imaging optics 6 are represented only schematically. They can be provided, in particular, as microscope optics, comprising objective optics and tube optics, and can, thus, comprise several optical imaging elements, wherein thebeam splitter 5 can be arranged between these imaging elements (preferably in an infinite beam path). - The
measurement apparatus 1 further comprises amask stage 11, which is provided, for example, as an x-y stage, to allow positioning of predeterminedtest structures 12 of thelithographic mask 8 in the detection region of themeasurement apparatus 1. -
FIG. 2 schematically showsseveral test structures 12 in a top view of thelithographic mask 8. As is evident fromFIG. 2 , said test structures can be provided as crosses; the representation inFIG. 2 is not to scale, and the size of the test structures is shown strongly enlarged. Between the test structures, the mask structures (not shown) are present which are required for exposure of a wafer in a lithographic exposure apparatus. - For control of the
measurement apparatus 1, a control unit 14 (FIG. 1 ) is provided, which is connected to themask stage 11, to thedetector 9 and optionally also to the source ofradiation 2, as well as to thepolarization module 4. - The
optical system 13 of themeasurement apparatus 1 has the eigen polarization conditions Z1 and Z2 schematically represented inFIG. 1 . Both eigen polarization conditions Z1 and Z2 are linear polarization conditions, which are oriented in the x-direction as well as perpendicular to the drawing plane. These eigen polarizations conditions Z1 and Z2 may be caused, for example, by thebeam splitter 5. In order to simplify the description, theimaging optics 6 are regarded here as not influencing the polarization condition of the electromagnetic radiation transmitted through them. - Further, the polarization condition of the electromagnetic radiation 3 emitted by the source of
radiation 2 is indicated. As schematically indicated by the circle in the drawing, this may be, for example, a circular polarization PL. - The
polarization module 4 is adapted to convert the electromagnetic radiation 3 having said circular polarization into a linear polarization coinciding with the eigen polarization condition Z1, or to transmit only this component, so that the electromagnetic radiation incident on thebeam splitter 5 has a polarization P1 which coincides with the first eigen polarization condition Z1 of theoptical system 13. This has the advantageous effect that the polarization P2 of the electromagnetic radiation 3 in theillumination optics 7 is not changed. Of course, the polarization module may be adapted such that electromagnetic radiation of any polarization is converted to the eigen polarization condition of the optical system or only the corresponding component is transmitted. - The polarization condition of the magnetic radiation is not changed even by reflection at the
test structure 12, because a first eigen polarization condition T1 of the test structure coincides with the polarization condition P2 of the electromagnetic radiation incident on thetest structure 12. The first eigen polarization condition T1 of the test structure is represented together with the second eigen polarization condition T2 of the test structure inFIG. 2 (these are linear polarization conditions). - Also, the polarization P2, P3 of the reflected electromagnetic radiation passing through the
detection optics 10 is not modified, because thedetection optics 10 have the same eigen polarization conditions Z1 and Z2 as theillumination optics 7. The reflected radiation, having the linear polarization P3 schematically indicated inFIG. 1 , is then incident on thedetector 9. - By setting the polarization of the electromagnetic radiation 3 to one of the eigen polarization conditions Z1 of the optical system, polarization-dependent imaging errors can be minimized. Thereby, the test structure can be measured by the
measurement apparatus 1 with extreme precision. -
FIG. 3 shows an improvement of the measurement apparatus ofFIG. 1 , wherein the same elements are designated by the same reference numerals and, for description thereof, reference is made to the above statements. - In contrast to the
measurement apparatus 1 ofFIG. 1 , there is arranged, in theoptical system 13 between thebeam splitter 5 and theimaging optics 6 of themeasurement apparatus 1 inFIG. 3 , aneigen polarization unit 15 which causes the eigen polarization conditions Z1 and Z2 of theoptical system 13 to be elliptically polarized conditions. In this case, thepolarization module 4 is provided such that the electromagnetic radiation 3 coming from thepolarization module 4 is elliptically polarized (according to one of the eigen polarization conditions Z1 and Z2). Thus, the embodiment ofFIG. 3 also achieves the advantage that theoptical system 13 does not change the polarization condition which coincides with one of its eigen polarization conditions Z1, Z2. - In particular, this allows the eigen polarization conditions of the measurement system to be freely adapted to those of the structure to be examined. Moreover, the
eigen polarization unit 15 can be used to correct polarization aberrations such that a maximum polarization-dependent wavefront error of λ/10 or λ/50, or λ/100, respectively, is not exceeded. - The
eigen polarization unit 15 can be controllable such that different eigen polarization conditions can be set under the control of thecontrol unit 14. Preferably, these are defined depending on the eigen polarization conditions T1, T2 of thetest structures 12 to be examined.
Claims (25)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US12/517,583 US9134626B2 (en) | 2006-12-15 | 2007-11-20 | Microscope and microscopy method for space-resolved measurement of a predetermined structure, in particular a structure of a lithographic mask |
Applications Claiming Priority (6)
Application Number | Priority Date | Filing Date | Title |
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US87028706P | 2006-12-15 | 2006-12-15 | |
DE102006059435A DE102006059435A1 (en) | 2006-12-15 | 2006-12-15 | Microscope for position-resolved measurement of especially lithography mask has source of electromagnetic radiation of defined radiation, optical system that applies radiation to structure to be measured, forms image on detector |
DE102006059435 | 2006-12-15 | ||
DE102006059435.5 | 2006-12-15 | ||
PCT/EP2007/010044 WO2008071294A1 (en) | 2006-12-15 | 2007-11-20 | Microscope and microscopy method for space-resolved measurement of a predetermined structure, in particular a structure of a lithographic mask |
US12/517,583 US9134626B2 (en) | 2006-12-15 | 2007-11-20 | Microscope and microscopy method for space-resolved measurement of a predetermined structure, in particular a structure of a lithographic mask |
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US20100142042A1 true US20100142042A1 (en) | 2010-06-10 |
US9134626B2 US9134626B2 (en) | 2015-09-15 |
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US (1) | US9134626B2 (en) |
DE (1) | DE102006059435A1 (en) |
TW (1) | TW200835904A (en) |
WO (1) | WO2008071294A1 (en) |
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DE102008048660B4 (en) | 2008-09-22 | 2015-06-18 | Carl Zeiss Sms Gmbh | Method and device for measuring structures on photolithography masks |
DE102008049365A1 (en) | 2008-09-26 | 2010-04-01 | Carl Zeiss Sms Gmbh | Mask inspection microscope with variable illumination setting |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4795246A (en) * | 1987-07-30 | 1989-01-03 | Loro Albert | Differential interference contrast microscope using non-uniformly deformed plastic birefringent components |
US6111690A (en) * | 1997-01-23 | 2000-08-29 | Yokogawa Electric Corporation | Confocal microscopic equipment |
US20060146384A1 (en) * | 2003-05-13 | 2006-07-06 | Carl Zeiss Smt Ag | Optical beam transformation system and illumination system comprising an optical beam transformation system |
US20090040601A1 (en) * | 2005-05-18 | 2009-02-12 | Olympus Corporation | Polarization microscope |
Family Cites Families (2)
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JPH11249026A (en) | 1998-03-03 | 1999-09-17 | Nikon Corp | Polarization microscope |
JP2001356276A (en) | 2000-06-13 | 2001-12-26 | Nikon Corp | Polarizing microscope |
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2006
- 2006-12-15 DE DE102006059435A patent/DE102006059435A1/en not_active Withdrawn
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2007
- 2007-11-20 WO PCT/EP2007/010044 patent/WO2008071294A1/en active Application Filing
- 2007-11-20 US US12/517,583 patent/US9134626B2/en active Active
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Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4795246A (en) * | 1987-07-30 | 1989-01-03 | Loro Albert | Differential interference contrast microscope using non-uniformly deformed plastic birefringent components |
US6111690A (en) * | 1997-01-23 | 2000-08-29 | Yokogawa Electric Corporation | Confocal microscopic equipment |
US20060146384A1 (en) * | 2003-05-13 | 2006-07-06 | Carl Zeiss Smt Ag | Optical beam transformation system and illumination system comprising an optical beam transformation system |
US20090040601A1 (en) * | 2005-05-18 | 2009-02-12 | Olympus Corporation | Polarization microscope |
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US9134626B2 (en) | 2015-09-15 |
TW200835904A (en) | 2008-09-01 |
DE102006059435A1 (en) | 2008-06-19 |
WO2008071294A1 (en) | 2008-06-19 |
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